1. Field of the Invention
This invention relates to a wiring harness and instrument panel assembly provided in a motorcar, allowing an improved assembling and coupling process of various electrical equipment units and wiring harnesses in the instrument panel.
2. Description of the Prior Art
FIG. 11 shows a known instrument panel provided in a motorcar as disclosed in Japanese Patent Application Laid-open No. 5-77659. This consists of separately formed upper and lower resin panels 51, 52. In the engagement faces of the panels 51, 52 there are formed cavities such as air ducts 53, 54 or a wiring harness space 55. The space 55 receives a wiring harness 56 or is provided with an electric circuit made by coating an electrically conductive paint. The engagement of the panels 51, 52 accomplishes the simultaneous connection of the wiring harness. Further, the arrangement gives advantages in fabrication process such as forming, transportation, storage, and assembling.
The above-mentioned instrument panel consisting of the two panels requires none of a wiring harness fixing clamp, an enclosing protector and the like. This allows a great reduction in part number and in production man-hour for the instrument panel. However, the correct connection of the wiring harness to switches, meters, and electrical equipment units depends on the right engagement of the abutment faces of the panels 51, 52. Non-correct engagement of the faces may cause a gap, resulting in an unstable connection of the harness.
For achieving the right connection, application of a lead wire extending from the wiring harness 56 of the lower panel 52 may be proposed. But, in engagement of the upper and lower panels, this may causes jamming of the lead wire, and a noise may be generated by the lead wire with a slack during the vehicle's running.
Further, vehicle body vibration generated during running or by in collision may bring about electrically wrong continuity due to the sliding movement of electrical wires in the space 55. Moreover, air temperature around the instrument panel causes the instrument panel to thermally expand. This may break fine wire circuits (smaller than 0.3 square millimeter) used for a wiring harness in the instrument panel, or may require a careful maintenance thereof.